Dual pivot instrument for reduction of a fixation element and method of use

ABSTRACT

A spinal fixation element fixation reduction system is provided herein. In general, the system can include a cap element with a bore having a central axis extending therethrough wherein the cap element is configured to releasably engage any type of surgical device (e.g., an access sleeve, a vertebral body rotator, etc.). Further, the system can include a driver configured to be slidably and removably positioned through the cap element. The system can also include an actuator configured to apply a force to the driver substantially along the central axis of the cap element thereby moving the driver in a distal direction so as to effect reduction of a spinal fixation element into a bone anchor. Additionally, a method of reducing a spinal fixation element into a bone anchor is also provided wherein the method can be performed as a minimally invasive surgical procedure or as an open procedure.

FIELD OF USE

The present disclosure relates to systems and methods for reducing aspinal fixation element into a bone anchor.

BACKGROUND

Spinal fixation devices are used in orthopedic surgery to align and/orfix a desired relationship between adjacent vertebral bodies. Suchdevices typically include a spinal fixation element, such as arelatively rigid fixation rod, that is coupled to adjacent vertebrae byattaching the element to various anchoring devices, such as hooks,bolts, wires, or screws. The fixation rods can have a predeterminedcontour that has been designed according to the properties of the targetimplantation site, and once installed, the instrument holds thevertebrae in a desired spatial relationship, either until desiredhealing or spinal fusion has taken place, or for some longer period oftime.

Spinal fixation devices can be anchored to specific portions of thevertebra. Since each vertebra varies in shape and size, a variety ofanchoring devices have been developed to facilitate engagement of aparticular portion of the bone. Pedicle screw assemblies, for example,have a shape and size that is configured to engage pedicle bone. Suchscrews typically include a threaded shank that is adapted to be threadedinto a vertebra, and a head portion having a rod-receiving element,usually in the form of a U-shaped slot formed in the head. A set-screw,plug, or similar type of fastening mechanism, is used to lock thefixation rod into the rod-receiving head of the pedicle screw. In use,the shank portion of each screw is threaded into a vertebra, and onceproperly positioned, a fixation rod is seated through the rod-receivingmember of each screw and the rod is locked in place by tightening a capor other fastener mechanism to securely interconnect each screw and thefixation rod.

While current spinal fixation systems have proven effective,difficulties have been encountered in mounting rods into therod-receiving member of various fixation devices. In particular, it canbe difficult to align and seat the rod into the rod receiving portion ofadjacent fixation devices due to the positioning and rigidity of thevertebra into which the fixation device is mounted. Thus, the use of aspinal rod reduction device, also sometimes referred to as a spinal rodapproximator, is often required in order to grasp the head of thefixation device and reduce the rod into the rod-receiving head of thefixation device.

While several rod reduction devices are known in the art, some tend tobe difficult and very time-consuming to use. Accordingly, there is aneed for improved rod reduction systems and methods for seating a spinalrod, or other spinal fixation element, into one or more spinal implantsor fasteners.

SUMMARY

Systems and methods for reducing a spinal fixation element into a boneanchor are provided herein. More specifically, the presently disclosedembodiments provide a modular system having a drive mechanism configuredto apply a force substantially along a longitudinal axis of a driverwhich is slidably and removably coupled to the drive mechanism. Inresponse to such a force, the driver can slide in a distal directionalong a central axis of a surgical device (e.g., a percutaneous accessdevice, a vertebral body rotator, etc.) thereby reducing a spinalfixation element into a bone anchor. As will be described below, themodular nature of the system allows for easy and efficient coupling ofthe drive mechanism to any number of drivers of different sizes andshapes. Additionally, the drive mechanism can be configured to includevarious pivotable connections thereby optimizing the amount of forcebeing delivered substantially along the longitudinal axis of the driver(and along the central axis of the percutaneous axis device) therebyproviding a mechanical advantage over commonly used systems and/ormethods.

Various aspects of a spinal fixation element reduction system areprovided herein. In one aspect, the system comprises a cap elementhaving a proximal end and a distal end with a bore extendingtherethrough along a central axis thereof wherein the cap element can besized and configured to releasably engage a surgical sleeve (e.g., apercutaneous access device, a vertebral body rotator, etc.). The systemcan include a first support having a proximal handle portion and adistal end pivotally coupled to the cap element. Further, the system caninclude an actuator pivotally attached to the first support. Theactuator can include a yoke at a distal portion thereof and a graspingmember at a proximal end thereof. Further, the actuator can be effectiveto selectively move the yoke towards the cap element. In one embodiment,the first support and the actuator can be pivotally attached atintermediate portions in a scissors-like manner. In an exemplaryembodiment, the distal end of the cap element can be configured toreleasably engage the percutaneous access device and the distal end canfurther be rotatably engaged to the proximal end of the cap element. Inan exemplary embodiment, the actuator is oriented in a non-parallelmanner (e.g., substantially transverse) with respect to the central axisof the cap.

In an exemplary embodiment, the system can include a driver having adistal end, a proximal end, and a length extending therebetween. Thedriver can be removably and slidably disposed through the bore of thecap element. As will be described below, the distal end of the drivercan be configured to contact and reduce a spinal fixation element into abone anchor. Optionally, the distal end of the driver can also beconfigured to releasably engage a fastening element (e.g., a set screw)such that the driver can reduce the fixation element into the boneanchor and also secure the fixation element therein by coupling thefastening element into the bone anchor (e.g., a proximal receiving headof the bone anchor) and subsequently disengaging the fastening elementfrom the distal end of the driver. Various embodiments of the driver arealso provided which include various other features. For example, in oneembodiment, the driver can include at least one marking along the lengththereof wherein the marking can be configured to indicate the positionof the driver relative to the cap element. In use, such markings can beindicative of a depth of the distal end of the driver relative to apatient's anatomy. In one embodiment, the driver can include a rotatableflange being positioned between the cap element and the driver therebyreducing friction between the cap element and the driver as the driveris rotated so as to secure the fastening element into the bone screw. Asanother example, the driver can include a flange element (e.g., a yokeinterface) formed along a portion thereof configured to contact aportion of the drive mechanism thereby allowing the drive mechanism toexert a force on the driver substantially along the longitudinal axis ofthe driver.

As indicated above, the system can include an actuator capable ofapplying a linear force to the driver along the central axis of the capelement. For example, in response to an actuation force, the yoke of theactuator can be pivotally moved towards the cap element. In oneembodiment, the yoke can contact the flange element of the driver. Whilethe flange element can be configured in a variety of manners, in anexemplary embodiment, the flange element includes a proximal-facingsurface configured to abut the yoke as the yoke is moved towards the capelement. In an exemplary embodiment, the system can include a pivotablemember coupled to an inner surface of the yoke wherein the pivotablemember can be configured to remain substantially flush against theproximal-facing surface of the flange element as the yoke moves towardsthe cap element thereby providing numerous benefits such as reducingdissipation of the applied force as well as reducing any wear or damageto the yoke or the flange element of the driver.

Various embodiments of an actuator of the drive mechanism are alsoprovided herein. In an exemplary embodiment, the actuator can include abiasing mechanism in communication with the proximal handle portion ofthe first support and also in communication with the grasping memberthereby biasing the proximal handle portion away from the graspingmember. While the biasing mechanism can include virtually any type ofsuch mechanism, in an exemplary embodiment, the biasing mechanismincludes a first prong (e.g., a leaf spring) extending from the proximalhandle portion of the first support and a second prong (e.g., a leafspring) extending from the grasping member wherein a distal portion ofthe first prong is configured to engage a distal portion of the secondprong. Optionally, the actuator can include a locking mechanismconfigured to maintain a position of the proximal handle portion of thefirst support relative to a position of the grasping member. Like thebiasing mechanism, the locking mechanism can also include virtually anytype of mechanism capable of controlling the position of the proximalhandle portion of the first member relative to the grasping member. Forexample, the locking mechanism can include an elongate member having aproximal end pivotally coupled to the proximal handle portion of thefirst support and having a distal end which includes at least one pawlconfigured to releasably engage a notch or groove formed in the graspingmember. In other embodiments, the locking mechanism can include aplurality of teeth or pawls formed along the length of the elongatemember thereby allowing for incremental changes in position of theproximal handle portion of the first support relative to the graspingmember.

In another aspect, a system is provided which includes a modular spinalfixation element reduction system comprising a drive mechanism having acap element with a bore extending therethrough having a central axiswherein the cap element is configured to releasably engage a proximalportion of a surgical sleeve. Further, the system includes a driver thatis configured to be removably and slidably disposed through the bore ofthe cap element wherein the drive mechanism is effective to deliver aforce to the driver along the central axis of the cap element therebycausing the driver to slide distally from a first position to a secondposition. As described above, the driver can include a distal end whichis effective to contact a spinal fixation element and upon distalmovement of the driver along the central axis, seat the spinal fixationelement within a bone anchor. Optionally, the system can further includea fastening element removably attached to the distal end of the driverand configured to lock a spinal fixation element within a bone anchor.

Various embodiments of such a drive mechanism are provided herein. Forexample, as described above, the drive mechanism can include a firstsupport having a proximal handle portion and a distal portion pivotallycoupled to the cap element. Further, the drive mechanism can include anactuator being pivotally engaged to the first support such that a yokeelement formed at a distal end of the actuator resides at a biasedposition above the cap element. Further, the actuator can also beconfigured to allow the yoke element to pivotally move towards the capelement in response to an actuation force.

The driver can also include a yoke interface (e.g., a flange element)formed on a portion thereof wherein the yoke interface is configured tocontact the yoke as the yoke pivotally moves toward the cap element.While the yoke interface can include virtually any configuration capableof being acting upon by the yoke, in an exemplary embodiment the yokeinterface is a flange element having a substantially planar proximalfacing surface. Optionally, the yoke can further include a pivotablemember coupled to an inner surface of the yoke such wherein thepivotable member can be configured to remain substantially flush withthe substantially planar proximal facing surface of the yoke interfaceas the yoke pivots toward the cap element.

Various aspects of a method for reducing a spinal fixation element intoa bone anchor are also provided herein. In one aspect, a method forreducing a spinal fixation element into a bone anchor is provided whichincludes attaching a drive mechanism to a surgical sleeve (e.g., apercutaneous access device, vertebral body rotator, etc.) and removablycoupling a driver to the drive mechanism such that the driver extendsinto the surgical sleeve. Thereafter, the drive mechanism can beattached to apply a force to the driver causing the driver to contact aspinal fixation element and to slide linearly and along a central axisin a distal direction of the surgical sleeve thereby reducing the spinalfixation element into a bone anchor. In an exemplary embodiment, theattaching step can further include rotatably attaching the drivemechanism to the surgical sleeve. Optionally, the method can furtherinclude releasably engaging a fastening element to a distal end of thedriver, coupling the fastening element to a proximal portion of the boneanchor, and disengaging the fastening element from the distal portion ofthe driver. Also, the method can be configured such that the attaching,coupling, and actuating steps summarized above (or at least one suchstep) can be performed as a minimally invasive surgical procedure.Alternatively, any of these steps (or all) can be performed as an opensurgical procedure.

In another aspect, a method for reducing a spinal fixation element intoa bone anchor is provided which includes removably attaching a capelement to a proximal portion of a percutaneous access device having acentral axis extending therethrough wherein the cap element includes abore with a central axis which is substantially collinear with thecentral axis of the percutaneous axis device. The cap element canfurther be pivotally coupled to a distal portion of a first supportwherein the first support is pivotally coupled to an actuator in ascissors-like manner. The method can further include removably couplinga driver to the actuator such that the driver extends through the boreof the cap element along the central axis of the bore and resides atleast partially disposed within the percutaneous access device. Likeabove, the driver can include a yoke interface formed along a portionthereof. The method can also include positioning a yoke formed on adistal portion of the actuator above the cap element. Additionally, themethod can include supplying an actuation force to the actuator to movethe yoke towards the cap element such that the yoke contacts the yokeinterface of the driver to cause the driver to slide linearly and alongthe central axis in a distal direction of the percutaneous access devicethereby reducing a spinal fixation element into a bone anchor.

These aspects, as well as others, are described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The systems and methods disclosed herein will be more fully understoodfrom the following detailed description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a perspective view of an exemplary embodiment of a drivemechanism;

FIG. 2 is a perspective view of a distal portion of the drive mechanismof FIG. 1;

FIG. 3 is an exploded view of the drive mechanism of FIG. 1;

FIG. 4A is a perspective view of an exemplary embodiment of a driver;

FIG. 4B is an exploded view of the driver of FIG. 4A;

FIG. 5A is a perspective view of an another exemplary embodiment of adriver;

FIG. 5B is an exploded view of the driver of FIG. 5A;

FIG. 6A is a representation of a plurality of percutaneous accessdevices engaged to a plurality of vertebrae;

FIG. 6B is a representation of an exemplary embodiment of a drivemechanism attached to a first percutaneous access device;

FIG. 6C is a representation of an exemplary embodiment of a driver beingcoupled to the drive mechanism of FIG. 6B; and

FIG. 6D is a representation of an actuation force being applied to thedrive mechanism of FIG. 6C.

DETAILED DESCRIPTION

Certain exemplary embodiments will now be described to provide anoverall understanding of the principles of the structure, function,manufacture, and use of the systems and methods disclosed herein. One ormore examples of these embodiments are illustrated in the accompanyingdrawings. Those skilled in the art will understand that the systems andmethods specifically described herein and illustrated in theaccompanying drawings are non-limiting exemplary embodiments and thatthe scope of the present disclosure is defined solely by the claims. Thefeatures illustrated or described in connection with one exemplaryembodiment may be combined with the features of other embodiments. Suchmodifications and variations are intended to be included within thescope of the present disclosure.

Various embodiments of a system and method for reducing a spinalfixation element into a bone anchor are provided herein. In general, thevarious embodiments provide an easy and efficient system and method ofcoupling a drive mechanism to various types and sizes of drivers. Forexample, the driver can be coupled to the drive mechanism by slidablyand removably positioning the driver through a bore of a cap element ofthe drive mechanism. Following a successful reduction, the driver isremoved from the drive mechanism and the procedure can be repeated at adistinct anatomical location. Additionally, the drive mechanism can beconfigured to concentrate an applied linear force along a longitudinalaxis of the driver thereby sliding the driver in a distal direction.Thus, minimal force is dissipated or wasted while reducing the spinalfixation element into a bone anchor. Additionally, a mechanicaladvantage supplied by the presently disclosed system can be furtherenhanced by incorporating various pivotable members into a drivemechanism of the system such that a portion of the drive mechanism incontact with the driver can pivot with the driver during application ofthe linear force thereby reducing any dissipation of such force and alsoreducing any wear or damage to the components of the system.

FIG. 1 shows an exemplary embodiment of a drive mechanism 10. As anoverview, the drive mechanism 10 can include a cap element 12 configuredto releasably engage a proximal portion of a surgical sleeve or surgicaldevice engaged to a vertebra (e.g., a percutaneous access device, avertebral body rotator, etc.). Further, the drive mechanism 10 caninclude a first support 14 having a proximal handle portion 16 and beingcoupled to the cap element 12 at a distal end 14 _(D) thereof. Further,the drive mechanism 10 can include an actuator 18 having a yoke 20 at adistal end and a grasping member 22 formed at a proximal portionthereof. In an exemplary embodiment, the actuator 18 is pivotablycoupled to the first support 14 at a pivot point 44, which may be at anintermediate location of the actuator 18 and the first support 14, in ascissors-like manner. Thus, in response to an actuation force beingapplied to the actuator 18 (e.g., the handle portion 16 of the firstmember 14 being pivotally moved towards the grasping member 22), theyoke 20 can be driven towards the cap element 12 which enables the yoke20 to contact a driver disposed through the cap element 12 therebyresulting in reduction of a spinal fixation element into a bone anchor.The actuator 18 can also include a biasing mechanism 24 extendingbetween the proximal handle portion 16 of the first support 14 and thegrasping member 22 to bias the handle portion 16 and the grasping member22 apart from each other. The actuator 18 can also include a lockingmechanism 30 configured to maintain a position of the proximal handleportion 16 relative to the grasping member 22.

FIGS. 1-3 provide an exemplary embodiment of a cap element 12 of thedrive mechanism 10. In general, the cap mechanism 12 can include anyelement being sized and configured to releasably engage a surgicalsleeve (e.g., a percutaneous access device) and also having a boreextending therethrough which is configured to allow a driver (see FIGS.4A-5B) to slidably pass therethrough. Thus, in an exemplary embodiment,the cap element 12 includes a proximal end 12 _(P), a distal end 12_(D), and a bore extending therebetween having a central axis (A). Thebore can be sized and configured to allow a driver (see FIG. 4A) to beslidably and removably disposed therethrough such that a longitudinalaxis of the driver is substantially collinear with the central axis (A)of the bore.

Referring to FIGS. 2-3, the cap element 12 can include a distal opening13 having a diameter (D) sized and configured to receive a proximal endof a surgical sleeve (e.g., a percutaneous access device). As the capelement 12 is advanced distally over the proximal portion of, forexample, the percutaneous access device (see FIG. 6A-6D), the capelement 12 can be configured to releasably engage the proximal portionof the percutaneous access device. As will be apparent to those skilledin the art, the cap element 12 can be configured in various manners soas to releasably engage the percutaneous access device. For example, asshown, the cap element 12 can include at least one (shown as two) biasedlever elements 36 coupled to a housing 12′ of the cap element 12. Inuse, a protrusion 41 formed on a distal portion 36 _(D) of the lever 36can snap into a corresponding opening (opening 41 shown in FIG. 6A) inthe proximal end of the percutaneous access device thereby releasablyengaging the cap element 12 to the percutaneous access device. Torelease this connection, a user can compress a proximal portion 36 _(P)of the lever 36 thereby rotating the lever 36 about a central fulcrum 37which removes the protrusion 41 from the opening of the percutaneousaccess device. As will be apparent to those skilled in the art, suchlevers 36 can be biased as such in virtually any manner capable ofproviding the desired effect. As shown in FIG. 3, a spring element 35,35′ can be coupled to each lever 36, 36′ thereby biasing each lever 36,36′ in the desired orientation.

In an exemplary embodiment, the cap element 12 can be configured suchthat the proximal portion 12 _(P) of the cap element 12 is rotatablycoupled to the distal portion 12 _(D) of the cap element 12. In such anembodiment, the distal portion 12 _(D) of the cap element 12 can beconfigured to releasably engage the percutaneous access device therebyallowing the remainder of the drive mechanism 10 to rotate relative tothe distal portion 12 _(D) and to the percutaneous access device and adriver disposed therethrough. In use, such a rotatable coupling canfacilitate a surgeon's ability to engage the cap element 12 to thepercutaneous access device, couple the drive mechanism 10 to a driver,and/or to supply an actuation force to the actuator 18. As apparent tothose skilled in the art, such a rotatable coupling can be provided invirtually any such manner capable of providing the desired effect. Forexample, as illustrated in the exemplary embodiment of FIG. 3, theproximal end 12 _(P) of the cap element 12 can include a rotatablemember 54 that is coupled to the distal portion 12 _(D) of the capelement 12 via a connector 56 thereby allowing the distal end 12 _(D) ofthe cap element 12 to rotate relative to the proximal end 12 _(P) of thecap element 12. Further, the proximal portion 12 _(P) of the cap element12 can be indexed (e.g., secured via a snap-fit every 90°) relative tothe distal portion 12 _(D) of the cap element 12 thereby indicating arelative position of the proximal end 12 _(P) to the distal end 12 _(D)during rotation.

The system further includes a first support 14 having a proximal handleportion 16 and a distal end 14 _(D) coupled to the cap element 12. Thecap element 12 can be coupled to the distal end 14 _(D) of the firstsupport 14 by virtually any manner or mechanism known to those skilledin the art. In one embodiment, the distal end 14 _(D) of the firstsupport 14 can be rigidly engaged to the cap element 12. However, in anexemplary embodiment, the distal end 14 _(D) of the first support 14 canbe pivotally coupled to the cap element 12 at a pivot point 42. As willbe described below, such a pivotable coupling can focus an applied forcealong a longitudinal axis of a driver thereby optimizes a mechanicaladvantage provided by the drive mechanism 10. It will be apparent tothose skilled in the art that various mechanisms and/or coupling can beutilized so as to pivotally couple the cap element 12 to the distal end14 _(D) of the first support 14. For example, as shown in FIG. 3, thedistal end 14 _(D) of the first support 14 can include first and secondopenings 59 which can be configured to be aligned and positioned onopposite sides of an opening 59′ formed in the proximal portion 12 _(P)of the cap element 12. Once aligned as such, a set screw or pin (notshown) can be secured through the openings 59, 59′ thereby securing thecap element 12 to the distal end 14 _(D) of the first support 14 whilealso allowing for the cap element 12 to pivot at a pivot point 42relative to the first support 14.

The system can further include an actuator 18 configured to cooperatewith the first support 14 to apply a linear force substantially along alongitudinal axis of a driver that is slidably and removably disposedthrough the cap element 12. As described below, the application of suchforce can effectively reduce a spinal fixation element into acorresponding bone anchor. In general, the actuator 18 can be anymechanism capable of applying such a linear force to the driver whereinthe force is supplied substantially along the longitudinal axis of thedriver and also substantially along the central axis (A) of the capelement 12 thereby sliding the driver distally from a first location toa second location so as to provide the desired reduction procedure.Various aspects of such an actuator of the drive mechanism are describedbelow.

FIGS. 1-3 provide an exemplary embodiment of an actuator 18 configuredfor use with the presently disclosed system. As shown, the actuator 18can include a yoke 20 formed at a distal end thereof and a graspingmember 22 formed at a proximal end. The actuator 18 can be coupled tothe first support 14 at various locations, in various manners, toprovide various configurations. However, in an exemplary embodiment, theactuator 18 can be coupled to the first support 14 at an intermediatelocation (e.g., pivot point 44) in a scissors-like manner. Similar tothe pivotal coupling of the cap element 12 to the distal end 14 _(D) ofthe first support 14, the actuator 18 can be pivotably coupled to thefirst member 14 in virtually any manner capable of providing the desiredeffect. For example, as shown, the actuator 18 can include an opening45′ along at an intermediate location thereof, and the first support 14can also include a corresponding opening 45 at a correspondingintermediate location thereof. Once positioned as such, another setscrew 43 can be disposed through the corresponding openings 45, 45′thereby securing the actuator 18 to the first support 14 while alsoallowing for the first support 14 to pivotally move relative to theactuator 18. In other embodiments, the actuator can be configured in atrigger configuration, a trigger-like configuration, or any other suchconfiguration capable of forcing the yoke element into contact with adriver coupled to the drive mechanism.

As indicated, the actuator 18 can include a yoke 20 formed at a distalend thereof that is configured to exert a downward, linear force on adriver disposed in the yoke and extending through a bore of the capelement 12. More specifically, during actuation of the actuator 18, theyoke 20 can be pivotally moved towards the cap element 12 and can beconfigured to contact a portion of a driver thereby reducing a spinalfixation into a bone anchor. As will be apparent to those skilled in theart, the yoke 20 can be of virtually any shape, size, and/orconfiguration capable of contacting the driver as the yoke 20 pivotallymoves towards the cap element 12 thereby applying the desired downwardforce to the driver. In an exemplary embodiment, the yoke 20 can be inthe form of a C-shaped element having a central opening 20 _(O) sizedand configured to receive a driver such that, as shown in FIG. 6C, thedriver can extend through the central opening 20 _(O) of the yoke 20.Also, the yoke 20 can be sized and configured to engage (e.g., abut) aportion of the driver (e.g., a yoke interface, discussed below) as theyoke 20 is pivotally moved towards the cap element 12.

In an exemplary embodiment, the yoke 20 can be configured to remainsubstantially flush with a portion of a driver as the yoke 20 pivotallymoves toward the cap element 12 thereby optimizing the mechanicaladvantage provided by the drive mechanism 10 while also reducing anyamount of wear and/or damage to the driver and/or yoke 20. As will beappreciated by those skilled in the art, the yoke 20 can be configuredin various manners to allow for such a flush contact between the yokeelement and a corresponding portion of the driver (e.g., a yokeinterface, described in greater detail below). For example, in oneembodiment, a pivotable member 50 can be coupled to an inner surface 20′of the yoke 20 such that the pivotable member 50 can pivot with acorresponding portion of a driver as the yoke 20 pivotally moves towardsthe cap element 12. Similar to the yoke 20 itself, the pivotable member50 can also have various sizes and/or configurations. Referring to FIG.2, the pivotable member 50 can be also be configured as a C-shapedelement being sized and configured to receive a driver. As will beappreciated by those skilled in the art, the pivotable member 50 can becoupled to the yoke 20 in virtually any manner capable of allowing themember 50 to pivot as described above. For example, as detailed in FIG.3, the pivotable member 50 can include a first opening 63 and a secondopening 63′ corresponding to first 51′ and second openings 49′ formed inthe yoke 20. Thus, a first set screw 51 can be disposed within the firstset of corresponding openings 63, 51′ and a second set screw 49 can bedisposed through the second set of corresponding openings 63′, 49′thereby providing the desired pivot functionality while also securingthe pivotable member 50 to the yoke 20.

The actuator 18 can also include a biasing mechanism 24 configured tomaintain the yoke 20 at a first, biased location relative to (e.g.,above) the cap element 12. As will be described, in response to theapplication of an actuation force sufficient to overcome the biasingforce, the yoke 20 will move from the biased position (e.g., as shown inFIG. 6C) to an unbiased position (e.g., as shown in FIG. 6D) therebymoving the yoke 20 towards the cap element 12 and thus into contact witha portion of a driver. As will be apparent to those skilled in the art,the biasing mechanism 24 can include any mechanism at any location ofthe drive mechanism that is capable of providing the desired effect. Inan exemplary embodiment, the biasing mechanism 24 can be incommunication with the proximal handle portion 16 of the first support14 and also in communication with the grasping member 22 of the actuator18 thereby applying a biasing force which is configured to push theseelements 16, 22 apart from one another. In other embodiments, thebiasing mechanism 24 can be in communication with the first support 14and the actuator 18 at a distal position relative to an engagement point44 between the first support 14 and actuator 18.

In one embodiment, the biasing mechanism 24 can include at least onespring or spring-like element (not shown) in communication with theproximal handle portion 16 of the first support and the grasping member22, a ratcheting mechanism (not shown) in communication with suchelements 16, 22, any type(s) of non-compliant material configured invarious manners to provide the desired effect on the handle portion 16and grasping member 22, etc. In the illustrated exemplary embodiment,the biasing mechanism 24 can include a first prong 26 (e.g., a leafspring) extending from the handle portion 16 and a second prong 28(e.g., a leaf spring) extending from the grasping member 22 wherein adistal end 26 _(D) of the first prong 26 is configured to receive adistal end 28 _(D) of the second prong 28. In such an embodiment, theprongs 26, 28 can be formed of any type(s) of non-compliant material(s)capable of exerting a force on each other such that the proximal handleportion 16 and the grasping member 18 are forced apart from one another.Those skilled in the art will appreciate that the prongs 26, 28 can beengaged or formed on respective handle portion 16 or grasping member 22in various manners. For example, as shown, the first prong 26 can beengaged to the handle portion 16 by at least one set screw 31 disposedthrough a corresponding number of holes 31′ in a distal end of the prong26 and secured in a corresponding opening 31″ formed in the firstsupport 14. Likewise, the second prong 28 can be engaged to the graspingmember 22 by at least one set screw 33 disposed through a correspondingnumber of holes 33′ in a distal end of the prong 28 and secured in acorresponding opening 33″ formed in the grasping member 22. In otherembodiments, the prongs 26, 28 can be welded into position.

The drive mechanism 10 can also include a locking mechanism configuredto maintain the position of the proximal handle portion 16 relative tothe position of the grasping member 22 and therefore maintaining theposition of the yoke 20 relative to the cap element 12. Like the biasingmechanism 24, the locking mechanism can include virtually any type ofmechanism disposed at virtually any location of the drive mechanism 10.In the illustrated exemplary embodiment, the locking mechanism caninclude an elongate member 30 having a proximal portion 30 _(P)extending from the proximal handle portion 16 and having a distal end 30_(D) configured to releasably engage the grasping member 22. As will beapparent to those skilled in the art, the distal portion 30 _(D) of theelongate member 30 and/or the grasping member 22 can be configured invarious manners to provide such a releasable engagement. For example,the distal portion 30 _(D) of the elongate member 30 can include aprotrusion, such as a pawl 32, capable of releasably engaging a groove32′ formed in the grasping member 22. In other embodiments, the elongatemember 30 can include a plurality of such protrusions (not shown)incorporated along any desired length of the elongate member therebyallowing the position of the proximal handle portion 16 to be lockedrelative to the position of the grasping member 22 at various stages.Similarly, the grasping member can include a plurality of grooves. Inanother embodiment, the locking mechanism can include a speed-nutelement configured to abut either the grasping member 22 of the proximalhandle portion as the handle 16 and member 22 move towards one another.

In addition to the various embodiments of a drive mechanism 10 describedabove, the system can also include a driver 100 configured to beslidably and removably disposed in the yoke to extend through a capelement 12 of the drive mechanism 10 such that a longitudinal axis (A′)of the driver 100 is substantially collinear with the central axis (A)of a bore of the cap element 12. Once so positioned, the drive mechanism10 can apply a force to the driver 100 substantially along the centralaxis (A) of the cap element 12 thereby optimizing the mechanicaladvantage provided by the drive mechanism 10. FIGS. 4A-4B provide anexemplary embodiment of a driver 100. As shown, the driver 100 caninclude a proximal end 100 _(P), a distal end 100 _(D), and a length (L)therebeween which can be selected in light of the requirements of thesurgical procedure and/or the patient's anatomy. As shown in FIG. 4B,the proximal end 100 _(P) of the driver 100 can be configured toreleasably engage a handle 102 configured to facilitate a user's abilityto manipulate the driver 100. For example, the use of such a handle 102can facilitate a user's ability to rotate the driver 100 which, asdescribed in detail below, can allow the distal end 100 _(D) of thedriver 100 to reduce a fixation element into a bone anchor and/or engagea fastening element to the bone anchor following such reduction. As willbe apparent to those skilled in the art, the handle 102 can bereleasably engaged to the proximal portion 100 _(P) of the driver 100 invirtually any manner capable of providing the desired effect. In anotherembodiment, a handle portion 102 can be welded onto the proximal portion100 _(P). In yet another embodiment, the driver 100 does not include anytype of handle portion.

The distal end 100 _(D) of the driver 100 can also be configured invarious manners to provide various functions. For example, in anexemplary embodiment, the distal end 100 _(D) can be configured tocontact and manipulate a spinal fixation element disposed between thedistal end 100 _(D) and a bone anchor such that in response to anactuation force supplied by the drive mechanism 10 (as described above),the distal end 100 _(D) of the driver 100 can effectively reduce thespinal fixation element into the corresponding bone anchor. Referringagain to FIG. 4B, the distal portion 100 _(D) of the driver 100 caninclude a flange-like element 112 coupled within a distal opening 110via a connector 114. In an exemplary embodiment, the flange-like element112 can be welded into position once disposed within the distal opening110. In another embodiment, the distal end 100 _(D) of the driver is asingle piece which extends to the proximal end 100 _(P) of the driver100.

In another exemplary embodiment, the distal end 100 _(D) of the driver100 can be configured to releasably engage a fastening element (e.g., aset screw or pin). Thus, in such an embodiment, after reducing thespinal fixation element into a bone anchor, the driver 100 can beconfigured to secure a fastening element to a proximal portion of thebone anchor and subsequently disengage the fastening element from thedistal end 100 _(D) of the driver 100 thereby securing the fasteningelement within the bone screw. As will be apparent to those skilled inthe art, various such techniques can be utilized to releasably engagethe fastening element to the distal end 100 _(D) of the driver 100.

As described above, the driver 100 can also include a yoke interface 104configured to abut the yoke 20 as the yoke 20 pivotally moves toward thecap element 12. Those skilled in the art will appreciate that such ayoke interface 104 can be sized and configured in virtually any mannercapable of contacting the yoke 20 as described above. It will also beappreciated that the yoke interface 104 can be formed along any locationof the driver 100 capable of providing the desired effect. In theexemplary embodiment, shown in FIG. 4A, the yoke interface 104 is aflange element formed on the driver 100. More specifically, the flangeelement 104 can include a substantially flat proximal-facing surface 106capable of receiving the yoke 20 as the yoke 20 is pivotally movestowards the cap element 12. In another embodiment, the yoke interfacecan be formed as ball and the yoke can be configured as a socket-typeelement thereby providing a ball-in-socket type engagement. As describedabove, in an exemplary embodiment, the substantially flatproximal-facing surface 106 of the flange element 104 can receive thepivotable member 50 coupled to the inner surface 20′ of the yoke 20 suchthat the pivotable member 50 can remain substantially flush against thesurface 106 as the force is supplied to the driver 100.

The driver 100 can also include various other features capable ofoptimizing a surgical procedure. For example, the driver 100 can includeat least one or a plurality of markings 118 which can be indicative of adepth of a distal end 100 _(D) of the driver 100 relative to a patient'sanatomy or indicative to the position of the driver 100 relative to thecap element 12. In another exemplary embodiment shown in FIGS. 5A and5B, the driver 100′ can include a rotatable flange element 130positioned adjacent and proximal to the yoke interface 104. In such anembodiment, the rotatable flange 130 can reduce rotational friction asthe driver 100′ is rotated in order to, for example, secure a fasteningelement to a bone anchor. As will be apparent to those skilled in theart, such a rotation flange 130 can be rotatably coupled to the driver100′ in virtually any manner capable of providing the desire effect. Forexample, as shown in FIG. 5B, the flange 130 can include an opening 131′configured to receive a set screw 131 such that a distal portion of theset screw 131 can be disposed in a groove 134 extending along an outercircumference of the driver 100′ thereby allowing the driver 100′ torotate relative to the flange 130.

Various embodiments of a method for reducing a spinal fixation elementinto a bone anchor are also provided herein. In general, the method caninclude releasably engaging a drive mechanism to some type of surgicalsleeve (e.g., a percutaneous access device, a bone anchor, a vertebralbody rotator, etc.), slidably and removably coupling a driver to thedrive mechanism and the surgical sleeve, and actuating an actuator ofthe drive mechanism so as to apply a force to a driver along a centralaxis of the cap element thereby reducing a spinal fixation element intothe bone anchor. The method can be configured for use in minimallyinvasive surgical procedures (e.g., with the use of percutaneous accessdevices) or the method can be configured for use in open procedures(e.g., with the use of a vertebral body rotator). In some embodiments,the method can also include releasably engaging a fastening element to adistal end of a driver, securing such the fastening element to a boneanchor, and disengaging the fastening element from the distal end of thedriver thereby securing the spinal fixation element within the boneanchor.

FIGS. 6A-6D provide an exemplary embodiment of a method in which a drivemechanism 10 can deliver a force to a driver thereby reducing a spinalfixation element 150 into a bone anchor B₁ that is engaged to apercutaneous access device 160. Referring to FIG. 6A, the method caninclude engaging a plurality of bone anchors B₁, B₂, B₃, B₄, B₅ to aplurality of vertebrae V₁, V₂, V₃, V₄, V₅ wherein the bone anchors B₁,B₂, B₃, B₄, B₅ are releasably engaged to a plurality of correspondingpercutaneous access devices 160, 162, 164, 166, 168. As will beappreciated by those skilled in the art, each bone anchor B₁ can includevirtually any such element configured to securely engage a vertebra V₁and having a proximal portion configured to receive a spinal fixationelement (e.g., a fixation rod) 150. Typically, such a bone anchor B₁ caninclude a threaded shank (not shown) polyaxially coupled to a U-shapedreceiving head configured to receive a spinal fixation element 150.Further, the receiving head can also include a series of threads B_(T)(which can be internal or external) configured to securely receive acorresponding series of threads formed on a fastening element therebyallowing the fastening element to securely retain the spinal fixationelement 150 within the bone anchor B₁. As will be appreciated by thoseskilled in the art, each percutaneous access device 160 can include anyaccess sleeve having an inner lumen configured to provide access from aproximal end 160 _(P) thereof to the bone anchor B₁. Thus, the length,size, shape, diameter, and/or configuration of the access device 160 canvary depending on the nature of the procedure and the patient's anatomy.As further shown in FIG. 6A, a spinal fixation element 150 can bedisposed through a plurality of side-wall openings 161 formed in eachpercutaneous access device 160. However, as shown, at this stage of atypical procedure, the fixation element is generally positioned adistance D_(R) above a corresponding bone anchor B₂.

Referring to FIG. 6B, an exemplary embodiment of the drive mechanism 10can be releasably engaged a proximal portion of a percutaneous accessdevice 160 such that a central axis of a cap element can besubstantially collinear with a central axis of an inner lumen of thepercutaneous access device 160. As shown, the actuator 18 can beoriented in a non-parallel manner (e.g., substantially transverse) withrespect to the central axis of the bore of the cap element 12 therebyproviding enhanced maneuverability for the user. Also, as describedabove, the ability to rotate the proximal end 12 _(P) of the cap element12 (and all components engaged thereto) relative to the releasablyengaged percutaneous access device 160 further enhances the usabilityand maneuverability of the drive mechanism 10.

Referring now to FIG. 6C, an embodiment of a driver 100 can be slidablyand removably disposed through the yoke 20 to extend through the bore ofthe cap element 12 and into an inner lumen of the percutaneous accessdevice 160. In such an embodiment, the driver 100 can slide distallyuntil a distal end 100 _(D) of the driver 100 is positioned above andadjacent to the spinal fixation element 150. Further, as shown, the yoke20 of the drive mechanism 10 can be positioned above and adjacent to ayoke interface 104 of the driver 100.

FIG. 6D shows an actuation force (F) being supplied to the actuator 18to pivot the proximal handle portion 16 towards the grasping member 22.As described above, such an actuation force (F) causes the yoke 20 tomove into contact with the yoke interface 104 thereby applying adownward force (F′) along the longitudinal axis of the driver 100. Asthe driver 100 moves downwards, the distal end 100 _(D) of the driver100 can effect reduction of the spinal fixation element 150 into thecorresponding bone anchor B₁. Following a successful reduction, thedriver 100 can be slidably removed from the percutaneous access device160 and a fastening element can be delivered along the percutaneousaccess device via an accessory surgical device. Following such delivery,the fastening element can be engaged to the proximal portion of the boneanchor B, thereby securing the spinal fixation element 150 within thebone anchor B₁. In another exemplary embodiment, the fastening element200 (see FIG. 6C) can be releasably engaged to the distal end 100 _(D)of the driver 100 thereby allowing the driver 100 to effect reduction ofthe spinal fixation element 150, secure the fastening element 200 to thecorresponding bone anchor B₁, and disengage the distal end 100 _(D) ofthe driver 100 from the fastening element 200. In a further embodimentof the presently disclosed method, any of the above identified steps canbe repeated so as to reduce the spinal fixation element 150 into anynumber of additional bone anchors B₁, B₂, B₃, B₄, B₅, etc. extendingalong any desired length of the patient's spinal column.

One skilled in the art will appreciate further features and advantagesof the presently disclosed system and method based on theabove-described embodiments. Accordingly, the present disclosure is notto be limited by what has been particularly shown and described, exceptas indicated by the appended claims. All publications and referencescited herein are expressly incorporated herein by reference in theirentirety.

1. A spinal fixation element reduction system, comprising: a cap elementhaving a proximal end and a distal end with a bore extendingtherethrough along a central axis thereof, the cap element being sizedand configured to releasably engage a surgical sleeve; a first supporthaving a proximal handle portion and a distal end that is pivotallycoupled to the cap element; and an actuator pivotally attached to thefirst support, the actuator having a yoke at a distal portion thereofand a proximal grasping member, the actuator being effective toselectively move the yoke towards the cap element.
 2. The system ofclaim 1, wherein the first support and the actuator are pivotallyattached at intermediate portions in a scissors-like manner.
 3. Thesystem of claim 1, further comprising: a driver having a distal end, aproximal end, and a length extending therebetween, the driver beingconfigured to be slidably and removably disposed through the bore of thecap element.
 4. The system of claim 3, wherein the driver includes atleast one marking along the length thereof, the marking configured toindicate the position of the driver relative to the cap element.
 5. Thesystem of claim 3, wherein the actuator is effective to apply a linearforce to the driver along the central axis of the cap element.
 6. Thesystem of claim 5, further comprising: a flange element formed on aportion of the driver, the flange element having a proximal-facingsurface configured to abut the yoke element as the yoke element is movedtowards the cap element by actuation of the actuator.
 7. The system ofclaim 6, further comprising: a pivotable member coupled to an innersurface of the yoke element to interface with the flange element, thepivotable member being configured to remain substantially flush againstthe proximal-facing surface of the flange element as the yoke elementmoves towards the cap element.
 8. The system of claim 1, wherein thedistal end of the cap element is configured to releasably engage thesurgical sleeve, the distal portion of the cap element further beingrotatably coupled to the proximal end of the cap element.
 9. The systemof claim 1, wherein the actuator is oriented in a non-parallel mannerwith respect to the central axis of the cap element.
 10. The system ofclaim 1, wherein the actuator includes a biasing mechanism incommunication with the proximal handle portion of the first support andin communication with the grasping member thereby biasing the proximalhandle portion away from the grasping member.
 11. The system of claim10, wherein the biasing mechanism comprises a first prong extending fromthe proximal handle portion of the first support and a second prongextending from the grasping member, a distal portion of the first prongconfigured to engage a distal portion of the second prong.
 12. Thesystem of claim 10, further comprising: a locking mechanism configuredto maintain a position of the proximal handle portion of the firstsupport relative to a position of the grasping member.
 13. The system ofclaim 1, further comprising: a fastening element removably attached tothe distal end of the driver and configured to lock a spinal fixationelement within a bone anchor.
 14. The system of claim 1, wherein thedistal end of the driver is effective to contact a spinal fixationelement and upon distal movement of the driver along the central axis,seat the spinal fixation element within a bone anchor.
 15. A modularspinal fixation element reduction system, comprising: a drive mechanismhaving a cap element with a bore extending therethrough having a centralaxis, the cap element being configured to releasably engage a proximalportion of a surgical sleeve; and a driver slidably configured to beremovably disposed through the bore of the cap element, wherein thedrive mechanism is effective to deliver a force to the driver along thecentral axis of the cap element thereby causing the driver to slidedistally from a first position to a second position.
 16. The system ofclaim 15, wherein the drive mechanism further comprises: a first supporthaving a distal portion pivotally coupled to the cap element and aproximal handle portion; and an actuator pivotally engaged to the firstsupport such that a yoke element formed at a distal end of the actuatorresides at a biased position above the cap element, the actuator furtherconfigured to allow the yoke element to pivotally move towards the capelement in response to an actuation force.
 17. The system of claim 16,wherein the driver includes a yoke interface formed along a proximalportion thereof, the yoke interface configured to contact the yokeelement as the yoke element pivots toward the cap element.
 18. Thesystem of claim 17, wherein the yoke interface is a flange elementhaving a substantially planar proximal facing surface.
 19. The system ofclaim 18, wherein the yoke element further comprises a pivotable membercoupled to an inner surface thereof, the pivotable member configured toremain substantially flush with the substantially planar proximal facingsurface of the yoke interface as the yoke pivots toward the cap element.20. A method for reducing a spinal fixation element into a bone anchor,comprising: attaching a drive mechanism to a surgical sleeve; removablycoupling a driver to the drive mechanism such that the driver extendsinto the surgical sleeve; and actuating the drive mechanism to apply aforce to the driver causing the driver to contact a spinal fixationelement and to slide linearly and along a central axis in a distaldirection of the surgical sleeve thereby reducing the spinal fixationelement into a bone anchor.
 21. The method claim 20, wherein theattaching step further comprises: rotatably attaching the drivemechanism to the surgical sleeve.
 22. The method of claim 20, furthercomprising: releasably engaging a fastening element to a distal end ofthe driver; coupling the fastening element to a proximal portion of thebone anchor; and disengaging the fastening element from the distalportion of the driver.
 23. The method of claim 20, wherein theattaching, coupling, and actuating steps are performed as a minimallyinvasive surgical procedure.
 24. A method for reducing a spinal fixationelement into a bone anchor, comprising: removably attaching a capelement to a proximal portion of a percutaneous access device having acentral axis extending therethrough, the cap element having a bore witha central axis which is substantially collinear with the central axis ofthe percutaneous axis device, the cap element further being pivotallycoupled to a distal portion of a first support wherein the first supportis pivotally coupled to an actuator in a scissors-like manner; removablycoupling a driver to the actuator such that the driver extends throughthe bore of the cap element along the central axis of the bore andresides at least partially disposed within the percutaneous accessdevice, the driver having a yoke interface formed on a portion thereof,positioning a yoke element formed on a distal portion of the actuatorabove the cap element; and supplying an actuation force to the actuatorto move the yoke towards the cap element such that the yoke contacts theyoke interface of the driver to cause the driver to slide linearly andalong the central axis in a distal direction of the percutaneous accessdevice thereby reducing a spinal fixation element into a bone anchor.25. The method of claim 24, further comprising: releasably engaging afastening element to a distal end of the driver; coupling the fasteningelement into a proximal portion of the bone anchor; and disengaging thefastening element from the distal portion of the driver.